What we used in one factory where I worked was a bridge crane that ran on rails that were mounted on the floor. This was used to change the battery of 48 volt forklift trucks. You generally need 3 batteries per truck. When lifting the battery the 2 lifting cables need to pass through the ends of a spacer bar so that the 2 cable lift straight up and do not distort the case of the battery.
This also provided time for cleaning the battery tops. If the battery top is dirty there will be excess standby discharge leading to short battery life and the charger will be unable to fully charge the battery. First, disconnect battery from forklift and charger. Second, rinse top of battery with water hose and nozzle. Then use hot water mixed with sodium carbonate a.k.a. washing soda, sodium bicarbonate a.k.a. baking soda, and then with liquid dishwashing detergent works just as well as factory made sprays. Then, let mixture do its jobs, scrub the battery top a little, then rinse with hose and nozzle. Just be sure to be gentle enough with the hose and chemical mixture so as not to force it into the battery caps.
Some smaller forklift trucks have passive conveyor rollers underneath the battery and you pull up to the charging station, roll ou the old battery, push the truck about a foot, and roll in the new battery. Some charging stations use conveyor balls instead of rollers so that you can move rhte batteries in 2 directions thus saving on having to push the forklift or pallet jack with muscle power.
At one time Vienna, Austria extended their steetcar system using battery buses that towed a trailer with batteries in it. There were peiodic stations where a bus would drop off a drained battery trailer and pick up a new one. This also saved on the problem that trackless trolley buses have no equipment ground.
At one time the New York Central railroad had tripower switching locomotive for local train movement over street tracks in some parts of Nwe York City. These had 600 volt traction motors that could run off of 3 power sources:
1. The underrunning 660 volt 3rd rail of nonstreet right of ways. This did not recharge the battery as you need 700 to 750 volts to recharge a 600 volt lead acid battery.
2. A 600 volt lead acid battery - this was handy for confined areas that did not have a 3rd rail. This also worked for sidings that were too costly to electrify not to mention that a 3rd rail on customer property needed a local disconnect switch to prevent power theft and safety problems. The conductor or brakeman could forget to lock off the disconnect and interlocking the disconnect with the track switch would have been a nightmare. A third rail in say a scrapyard would be one hell of a problem even if of the inwsulated underrunning variety.
3. A 750 volt DC diesel generator that was used to recharge the batteries and power the traction motors when running on open streets where a 3rd rail is impractical.
The battery also helped with the matter that early diesel locomotives did not have a whole lot of power available from the engine.
Mike Cole
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